In this work, monodisperse nanoparticles and nanorods of lanthanum hydroxide was synthesized from the reaction of lanthanum(III) nitrate and sodium hydroxide by sonochemical method. The effect of some of the parameters such as feeding rate of precursors, different solvents of reaction, time of sonication, and various surfactants on the particle size and morphology of products was studied. The as-prepared products were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy.